1. Field of the Invention
The present invention is directed to a telecommunications system and method for handling call attempts directed to a mobile station, particularly to a system and method for determining when and how calls and/or calling party information is forwarded to the called party in mobile-terminated calls. The invention furthermore relates to a mobile station employing the proposed system and method according to the present invention.
2. Background and Objects of the Present Invention
Methods and systems for message delivery to mobile stations under insufficient or disturbed radio coverage are set forth in applicant's co-pending U.S. patent application Ser. No. 08/719,282, entitled "Subscriber Feature Controlled High Power Messaging", filed Sep. 24, 1996 and Ser. No. 08/931,625, entitled "System and Method for Forwarding Calling Party Information", filed Sep. 16, 1997, respectively. The former application discloses a system and method for overcoming signal path interference during the delivery of messages to mobile stations by increasing the power of at least the initial communications transmissions, thereby enabling satellite high-power notification of mobile stations that are unreachable via a terrestrially-based telecommunications system. The latter application describes a system and method for reducing the risk of seizing trunk lines for mobile-terminated call attempts, which are impossible to complete due to the fact that the mobile station receives insufficient radio energy (e.g., is shadowed), only has access to intolerably disturbed communication resources, or is detached from the telecommunications system. Hence, futile high-power notification messages are stopped before being sent to mobile stations that are unable to respond to them, e.g., mobile stations being powered off.
Generally, a high-power notification message does not result in a call being set up (due to poor communication conditions). It is, therefore, highly desirable for a subscriber to be reachable by the most important call and text message attempts when located at a position where a high-power notification message is the only way to contact the subscriber's mobile station.
Nevertheless, known solutions do not offer a mobile subscriber the possibility to indicate whether or not they wish to be reached via such high-power notification messages, nor do these solutions give an opportunity for the mobile subscriber to define which calling parties, if any, that shall be let through when the mobile station is located outside the coverage area of the terrestrially-based mobile telecommunications system.
An object of the present invention is thus to provide a method and a system for improved high-power notification in both terrestrially-based and satellite-based mobile telecommunications systems.
Particularly, it is an object of the invention to provide a call screening function through which a mobile subscriber may define what call attempts and attempts to send text messages to let through via a high-power notification service.
Yet a further object of the invention is to alert a user of a mobile station when the mobile station is located in an area where the terrestrially-based mobile telecommunications system within which the user is roaming provides insufficient coverage.